排序方式: 共有23条查询结果,搜索用时 15 毫秒
1.
A. Bensalah Y. Guyot M. Ito A. Brenier H. Sato T. Fukuda G. Boulon 《Optical Materials》2004,26(4):375
YLiF4 (YLF) single crystals undoped and Yb3+-doped with different concentrations were grown by the Czochralski technique under CF4 atmosphere. Detailed analysis of Yb3+-doped YLF spectroscopy were made to contribute to the determination of energy levels in this host. We are dealing with temperature and concentration dependences of both π and σ polarizations of the infrared (IR) absorption and emission spectra. Raman spectra were also used to give an attempt of interpretation of electronic and vibronic levels. The radiative energy transfer (self-trapping) and strong phonon–electron coupling make the assignment of Yb3+ energy levels difficult. Evaluation of the laser potentiality of this fluoride host is also presented. 相似文献
2.
3.
4.
Kheirréddine Lebbou Didier Perrodin Valery I. Chani Alain Brenier Olivier Tillement Ouassila Aloui Jean Marie Fourmigue Julien Didierjean François Balembois Patrick Gorges 《Journal of the American Ceramic Society》2006,89(1):75-80
The micro-pulling-down technique has been applied to produce undoped and 0.1% Nd3+ -doped Y3 Al5 O12 garnet single-crystal fibers with controlled diameter. The hot zone construction and fiber-pulling conditions have been optimized. As a result, growth of transparent and homogeneous fiber crystals has been achieved. The crystals have been grown under 105 Pa (1 atm) of argon atmosphere, with the pulling rate varied in the range of 0.3–2.0 mm/min. One hundred percent of the starting melt has been normally transformed into a crystalline material, with an empty crucible ready for the next growth procedure. The as-produced fibers demonstrate promising optical properties. 相似文献
5.
M. Boujelbene A. Moisan N. Tounsi B. Brenier 《International Journal of Machine Tools and Manufacture》2004,44(1):245
The challenge of die and mold milling is to achieve the specified dimensional and geometrical accuracy, and improve the surface roughness, in order to minimize polishing operations, still necessary to meet the tight tolerances required by the automotive industry and the plastic injection sector. The present study investigates the multi-axis milling of a specific mold steel grade Super Plast ® 300* (SP300) [1], by a ball nose carbide tool coated with Ti(CN). Surface finish analysis given by 3D measurements and data processing techniques shows that micro-geometrical defects generated by C1 continuous tool path are definitely less serious than those obtained by classical tool paths driven via linear interpolation. Also, polishing time saving is more than 30%. Thus, a substantial productivity enhancement is achieved in dies and molds manufacturing. 相似文献
6.
7.
Green fluorescence has been obtained under continuous laser excitation in the 780–860 nm range in GdAlO3:Er3+. With the help of the Judd-Ofelt treatment we built a model based on population rate equations to describe its time evolution. We found the intensity parameters to be Ω2 = 2.045 × 10−20 cm2, Ω4 = 1.356 × 10−20 cm2 Ω6 = 1. 125 × 10−20 cm2. Even if a two-photon absorption and a looping mechanism are necessary to well describe the dynamics, the main process responsible for up-conversion is energy transfer between erbium ions. 相似文献
8.
9.
R. Brenier B. Canut S. M. M. Ramos P. Thevenard 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》1994,90(1-4):339-343
-Al2O3 single crystals were bombarded with MeV xenon ions from 1015 to 1017 ions cm−2 and GeV uranium ions from 1011 to 1013 ions cm−2 to study the surface swelling of sapphire at 77 and 300 K due to atomic collision processes (Xe) and electronic energy loss processes in the 20–45 keV/nm regime (U). The induced damage was studied by channeling Rutherford backscattering. Surface swelling was measured with a profilometer. The step height induced by nuclear cascades of MeV xenon increases with the ion fluence and saturates. With GeV uranium, an electronic stopping power threshold for surface swelling was observed and the step height increased with the damage for dE/dx higher than this threshold. 相似文献
10.
A study is presented about Cr3+→Tm3+ energy transfers in Gd3Ga5O12 garnet at 10 K. By time-resolved spectroscopy and analysis of decay kinetics we determine the nature of the interaction and we show the existence of chromium-thulium pairs in which the chromium emission wavelength is shifted from 693.6 to 694 nm. 相似文献